What are intents and solvers? The invisible layer executing your DeFi trades

Introduction

Most DeFi users believe they interact directly with an automated market maker when they swap tokens on Uniswap or SushiSwap. In 2022, this was broadly true. A user signed a transaction, that transaction entered the public mempool, a validator included it in a block, and the AMM’s constant-product formula determined the price.

This model has a problem. Public mempools are hunting grounds. MEV bots monitor pending transactions and execute sandwich attacks: they buy before your trade pushes the price up, then sell after, extracting value from the spread. Flashbots estimated that MEV extraction on Ethereum exceeded $600 million in cumulative profit by 2023, with a significant share coming from sandwich attacks on retail swaps. For a deeper look at how this extraction works, see what is MEV.

Intent-based protocols restructure this flow. Instead of broadcasting a transaction that specifies every execution detail, the user signs an intent: a declarative statement of the desired result. A network of solvers then competes to fill that intent at the best possible price, off-chain, without exposing the order to the public mempool.

This guide explains the mechanics of intents and solvers, how the major protocols implement them, and what tradeoffs users accept.

The problem with direct AMM interaction

When a user swaps tokens through a traditional AMM, the transaction encodes a specific path: swap token A for token B on pool X, with a minimum output of Y, by deadline Z. This specificity creates three problems.

MEV vulnerability. The transaction sits in the public mempool until a validator includes it. During that window, bots can see the intended trade and sandwich it, extracting value from the user. Academic research from the Flashbots team documented that sandwich attacks cost retail users an estimated $200 million to $300 million annually on Ethereum alone. One particularly striking case saw a DeFi trader suffer 100% slippage in a sandwich attack, losing the entire value of the trade.

Suboptimal routing. A user submitting a transaction to a single AMM gets that AMM’s price. But liquidity is fragmented across dozens of DEXs, multiple chains, and centralized exchanges. The best price for a given swap might involve splitting the order across three pools on two chains, a route the user’s simple transaction never considers.

Gas inefficiency. Each user pays gas individually. If 50 users want to swap $ETH for $USDC in the same block, they submit 50 separate transactions, each paying its own gas overhead. There is no mechanism for batching.

How intents work

An intent inverts the transaction model. Instead of specifying how to execute a trade, the user specifies what they want to achieve.

A typical intent contains:

• Input token and amount. What the user is willing to spend.
• Output token and minimum amount. What the user wants to receive, with a floor price.
• Expiration. A deadline after which the intent expires.
• Signature. Cryptographic proof that the user authorized this intent.

The intent is not a blockchain transaction. It is an off-chain signed message, submitted to a protocol-specific order flow system instead of the Ethereum mempool. This distinction is crucial: because the intent never enters the public mempool, it is invisible to MEV bots scanning for sandwich opportunities.

Once submitted, the intent enters a solver auction. The signed message grants conditional approval for a settlement contract to transfer the user’s input tokens, but only when the solver delivers the promised output. The user’s funds remain in their wallet until the moment of atomic settlement.

What solvers do and how they compete

A solver is an entity (a bot, a market maker, a trading firm) that monitors incoming intents and competes to fill them.

The competition works differently across protocols, but the general structure is:

1. Intent broadcast. The protocol distributes new intents to registered solvers.
2. Solution generation. Each solver analyzes the intent and determines how to fill it. A solver might route through multiple DEX pools, tap private inventory, bridge from another chain, or combine several intents into a single batch.
3. Bid submission. Solvers submit their proposed execution, including the output the user will receive.
4. Auction resolution. The protocol selects the winning solver, typically the one offering the user the best price after all costs.
5. On-chain settlement. The winning solver executes the trade on-chain, and the settlement contract verifies that the user received at least the promised minimum output.

Solvers operate at their own risk. They front the capital, pay gas, and handle execution complexity. Their profit comes from the spread between the price they can source and the price they bid to the user, minus gas and capital costs. Competition between solvers compresses this margin, pushing more value back to users.

The economics of solver operation create a natural barrier to entry. Competitive solving requires capital for inventory, low-latency infrastructure for monitoring multiple liquidity sources, and sophisticated routing algorithms. The scale at which MEV bots operate illustrates the computational intensity of on-chain execution optimization. Solvers do the same work but channel the value toward users instead of extracting it.

CoW Protocol: batch auctions and coincidence of wants

CoW Protocol (formerly CowSwap) pioneered the intent-solver model on Ethereum. The name derives from “coincidence of wants” (CoW), a concept from economics.

The key innovation is batch auctions. Instead of filling orders one at a time, CoW Protocol collects intents over a window (approximately 30 seconds), then runs a single batch auction where solvers compete to fill all orders simultaneously.

This creates an opportunity for direct matching. If Alice wants to sell 1 $ETH for $USDC and Bob wants to buy 1 $ETH with $USDC, a solver can match them peer-to-peer without touching a liquidity pool. Neither party pays the AMM’s fee or spread. The solver profits by capturing the spread between the two users’ limit prices.

CoW Protocol calls this a “coincidence of wants” trade. In practice, pure CoW trades account for a meaningful minority of volume, but when they occur, both parties get prices better than any AMM can offer.

For orders that cannot be matched peer-to-peer, solvers route through on-chain liquidity. The batch auction format still helps: because all orders settle in a single transaction, gas costs are amortized across the batch. A batch of 30 swaps pays the fixed transaction overhead once, not 30 times.

By mid-2026, CoW Protocol had processed over $80 billion in cumulative volume, making it one of the largest DEX protocols by trade count. Its solver set has also matured, with established market makers and trading firms competing alongside independent solver operators.

UniswapX: Uniswap’s intent layer

UniswapX, launched in 2023, adds an intent-based execution layer on top of Uniswap’s existing liquidity pools.

When a user submits a swap through the Uniswap interface, they can opt into UniswapX. Instead of routing directly through Uniswap V3 or V4 pools, the swap becomes an intent. Solvers (called “fillers” in UniswapX terminology) compete to fill it.

UniswapX introduces Dutch order auctions. The user’s minimum acceptable output starts high and decays over time, following a predefined curve. The first solver willing to fill at the current price wins. This mechanism incentivizes solvers to fill quickly (they get a better margin early) while protecting users from receiving a bad price (the auction starts at an aggressive level).

A critical design choice: if no solver fills the order before it reaches the Uniswap pool price, the order automatically falls back to on-chain Uniswap routing. The user always gets at least the AMM price. Solvers can only win by offering something better.

UniswapX also introduces cross-chain intents. A user on Arbitrum can express an intent to receive tokens on Optimism. The solver handles the bridging, and the settlement contracts on both chains verify the outcome. From the user’s perspective, it is a single swap. This cross-chain capability was expanded in 2025 with permissionless bridging across nine networks, powered by the Across Protocol’s intent infrastructure.

Across: intents for cross-chain transfers

Across Protocol applies the intent-solver model specifically to cross-chain transfers.

Bridging tokens between chains traditionally involved lock-and-mint mechanisms, optimistic verification windows (often 7 days for optimistic rollups), or liquidity pool-based bridges. All of these are slow, expensive, or both.

Across restructures bridging as an intent. The user signs a message: “I have 1,000 $USDC on Ethereum and want 1,000 $USDC on Arbitrum.” A solver (called a “relayer” in Across) immediately sends 1,000 $USDC to the user on Arbitrum from its own inventory, then later claims reimbursement from Across’s settlement system on Ethereum.

The result: bridge times measured in seconds rather than minutes or days. The user does not wait for the cross-chain verification. The solver takes on that waiting risk in exchange for a fee.

Across’s verification layer uses an optimistic oracle ($UMA). If the solver’s claim is not disputed within a challenge window, the reimbursement is processed. This creates an economic game where honest relaying is profitable and fraudulent claims are punished by bond slashing.

Across’s collaboration with Uniswap on the Open Intents Framework aims to standardize how intents work across protocols, reducing the fragmentation that currently forces users to pick a specific intent system.

ERC-7683 and the standardization push

A major limitation of current intent systems is that each protocol defines its own intent format, solver network, and settlement contract. An intent submitted to CoW Protocol cannot be filled by a UniswapX solver. This fragmentation limits solver competition and reduces the pool of available liquidity for each system.

ERC-7683, proposed by Uniswap and Across in 2024, aims to create a universal standard for cross-chain intents. The proposal defines a common intent format (called a “CrossChainOrder”) that any protocol can adopt. Solvers who implement the standard can fill intents from any compliant protocol, increasing competition and improving prices.

The standard defines two interfaces: ISettlementContract (which settlement contracts implement) and IOriginSettler / IDestinationSettler (which handle cross-chain execution). By standardizing these interfaces, ERC-7683 would let a single solver operate across CoW Protocol, UniswapX, and Across simultaneously, competing for order flow from all three.

Adoption is still early. The standard requires existing protocols to modify their settlement contracts, which involves security audits and governance votes. But the direction is clear: intent-based trading is moving toward a unified solver marketplace instead of fragmented protocol-specific pools.

The tradeoffs of intent-based systems

Intent-based protocols improve user outcomes on price and MEV protection. They also introduce new trust assumptions and risks.

Solver centralization. In practice, a small number of well-capitalized solvers win most auctions. CoW Protocol’s solver leaderboard consistently shows 3 to 5 solvers handling the majority of volume. If solver competition weakens, users lose the price improvement that makes the system valuable.

Latency. Batch auctions and solver competitions add time between order submission and execution. CoW Protocol’s batches settle roughly every 30 seconds. UniswapX’s Dutch auctions resolve faster but still involve a delay. For time-sensitive trades, this latency can matter.

Solver trust. Users trust that the settlement contract correctly enforces the minimum output. The smart contracts are audited, but they are still smart contracts. Additionally, the off-chain auction mechanism must be fair. If the protocol operator can privilege certain solvers, the auction is not truly competitive.

Censorship risk. Because intents are submitted off-chain to protocol-specific systems, the protocol operator could theoretically censor certain intents. This is a different trust model than submitting transactions directly to Ethereum’s censorship-resistant mempool.

Regulatory attention. Solver networks that route order flow bear structural resemblance to broker-dealers in traditional finance. The question of whether solver activity constitutes regulated market making is unresolved. Regulatory clarity could either legitimize the model or impose compliance requirements that reduce the number of active solvers.

What this does not cover

This guide explains the core mechanism of intents and solvers. It does not cover:

• The technical implementation of specific solver algorithms
• Regulatory considerations around solver activity (order flow payment, best execution obligations)
• Detailed tokenomics of CoW Protocol (COW token) or $UMA (used by Across)
• The relationship between intents and Ethereum’s proposer-builder separation (PBS) roadmap

Practical checks before using intent-based protocols

Compare prices. Before submitting an intent, check the quoted output against direct AMM execution. Intent-based protocols should consistently offer better prices. If they do not, the solver auction may not be competitive.

Understand the fallback. UniswapX falls back to on-chain AMM routing if no solver fills the order. CoW Protocol expires unfilled orders. Know what happens if solvers do not execute your intent.

Check slippage tolerance. The minimum output in an intent functions like a slippage tolerance. Setting it too tight may result in unfilled orders. Setting it too loose gives solvers room to offer worse prices. Most interfaces set a default, but users can adjust it.

Verify the settlement contract. The smart contract that enforces intent execution is the critical trust component. Check whether it has been audited and by whom. Look for contracts that are immutable or governed by a time-locked multisig rather than a single admin key.

Consider order size. Intents offer the most price improvement for medium to large orders, where routing optimization and MEV protection have the greatest impact. For very small swaps on low-gas chains, the price improvement may be negligible because MEV extraction is less profitable on small orders.

Watch for gas overhead. On Ethereum mainnet, the settlement contract execution adds gas costs that may offset the price improvement for small trades. On Layer 2 networks where gas is cheap, this overhead is negligible. Compare the total cost (including gas) of an intent-based swap against a direct AMM trade to see the net benefit.

The future of intent-based trading

Intent-based architectures are expanding beyond simple token swaps. Several trends are emerging by mid-2026.

Multi-action intents. Current intents describe single operations (swap token A for token B). Next-generation systems allow compound intents: “swap A for B, deposit B into a lending protocol, and borrow C against it” as a single atomic intent. Solvers who can execute the entire sequence efficiently compete for the bundle.

AI-powered solvers. Machine learning models are being applied to solver optimization. An AI solver can predict short-term price movements, anticipate liquidity conditions across chains, and dynamically adjust routing strategies. The computational advantage of AI-powered solvers could accelerate the trend toward solver centralization, as only well-resourced teams can train and operate these models.

Intent-aware wallets. Wallets are beginning to default to intent-based execution for all swaps, making the intent layer invisible to users. MetaMask’s integration of Uniswap’s API for in-wallet swaps points toward a future where every wallet swap is automatically routed through a solver auction, with users seeing only the quoted price and confirmation.

Regulatory frameworks. As intent-based trading grows, regulators are beginning to examine whether solver activity constitutes regulated financial services. The Payment for Order Flow (PFOF) model in traditional equity markets has structural similarities to how some protocols compensate solvers. Regulatory clarity will shape whether intent-based trading remains permissionless or requires licensed participants.